The invention relates to an apparatus and method for making filter patch samples and for determining properties of particulates in a fluid.
Rotating and reciprocating equipment is subject to failure before the economic life of the equipment has been reached due to a variety of reasons. One reason for premature failure is misalignment of the equipment causing excessive wear to moving parts. Another cause of failure is an increase in particulate material in fluids used to lubricate the moving parts of the equipment. Still another cause of failure is due to chemical changes in tile lubricating fluid compositions caused by moisture, excessive heat or other liquid contaminants.
Despite the advances made in tile field of lubricant analysis, there continues to be a need for the ability to precisely quantify the level and size distribution of particulate contaminants in lubricating fluids as well as identifying the particulates which may cause premature failure of the equipment so that corrective action can be taken at the earliest possible date. There is also a need for a relatively simple analytical device which can be used in a field setting to determine the quantity of contaminants and the size distribution thereof in an oleaginous fluid with a relatively high level of confidence.
The present invention provides an analytical device for determining various quantitative and qualitative properties of particulate contaminants in a fluid which is relatively simple and which can be used on a variety of fluids for particulate analysis thereof. In one aspect the invention provides a sampling apparatus which includes a compression housing containing first and second housing members. A filter media holder having opposed surfaces and having an opening therethrough is disposed between the first and second housing members. At least one resilient sealing member is disposed adjacent each of the surfaces of the holder for scaling between the holder and the first and second housing members. At least one foraminous support is adjacent at least one surface of the holder. A porous medium is disposed adjacent the foraminous support and a medium sealing member is adjacent the porous medium and the first housing member. A clamping means is attached to the first and second housing members for clamping the holder and sealing members between the first and second housing members for forming a fluid tight seal thereby defining a closed volume through which fluids may flow. The first housing member includes a fluid inlet which is in flow communication with the opening, porous medium and foraminous support. The second housing member includes a fluid outlet which is in flow Communication with the opening, porous medium and foraminous support, whereby a fluid flow path is formed from the inlet, through the porous medium and out the outlet for depositing particulates on the porous medium to thereby produce a sample of the particulates in the fluid.
In another aspect, the invention provides an optical sample preparation device which includes a fluid inlet reservoir connected in flow communication with an inlet port attached to a filter patch device. The filter patch device includes a cylindrical member containing first and second annular recesses on opposing sides thereof and an opening therethrough in flow communication with the inlet port. At least one resilient sealing member is disposed in each of the recesses. At least one foraminous support is disposed in the cylindrical member over the opening adjacent the first recess. At least one porous medium is disposed adjacent the foraminous support between the foraminous support and the sealing member. A compression housing containing first and second housing members maintains the cylindrical member, sealing member, foraminous support and porous medium in compression between the first and second housing members by use of a clamping means for compressing the sealing members to form a fluid tight seal. A fluid inlet in the first housing member is in flow communication with the inlet port, the opening, the porous medium and the foraminous support. A fluid outlet in the second housing member in flow communication with the opening, porous medium and foraminous support. A vacuum source is connected in flow communication with the field outlet for drawing a sample through the sample preparation device.
Another aspect of the invention provides a method for preparing a filter patch sample for optical analysis which includes providing an optical sample preparation device containing a fluid inlet reservoir connected in flow communication with an inlet port attached to a sampling apparatus according to the first aspect of the invention. According to the method, a fluid sample to be analyzed is fed to the fluid inlet reservoir of the sampling apparatus. A pressure is applied to the sample with the vacuum source to draw the fluid through the porous medium of the sampling apparatus. Upon drawing all of the fluid in the inlet reservoir through the sampling apparatus, a solvent or gas is flowed through the porous medium so as to remove residual fluid therefrom. Upon removal of residual fluid from the medium, the clamping means is unclamped in order to remove the porous medium from the medium holder.
Still another aspect of the invention provides a method for determining quantitative or qualitative properties of particulate solids in an oleaginous. material. The method includes providing an oleaginous fluid sample, feeding the fluid sample to a fluid sample holder having a defined volume in flow communication with a dual filter patch device containing first and second porous media, applying a reduced pressure to the filter patch device to draw tile fluid sample sequentially through the porous media, removing residual fluid sample from the porous media using a solvent for the fluid, and optically observing particulate material on the porous media.
The invention provides a compact, highly effective apparatus for obtaining filter patch samples for quantitative and/or qualitative analysis. The apparatus provides a liquid tight sealing means and may be used to provide multiple filter patch samples essentially simultaneously for determination of properties of contaminants having different particle sizes.